 main index © Jeff Matthews 2002-2012 entry Apr 2010 Big
Archie & Living
on the Edge The
Archiflegrean Caldera is the area bounded
by the red lines with wedges. The area shown in the map is about 30 kilometers across.  I have
always known that the area is, volcanically, a
bit “iffy.” After all, from my balcony (about
where the word "Chiaia" is, above "Bay of
Naples" in this image) I can see Mt. Vesuvius
way over to the east. It (Vesuvius, not my
balcony), has been quiet, lo, these last 66
years. (And that’s just one 6 short of a hell
of a volcano!) But that’s only the tip of the
volcano. Vesuvius is a child (less than 20,000
years old) compared to the roaring
land-forming engines that earlier produced
almost everything else in this image: the
Fuorigrotta Plain and everything to the west
of the Posillipo hill until you get to Capo
Miseno, Monte di Procida, and Cuma
at the western end of the Gulf of Naples.
There are still remnants (Monte di Procida is
one) of the cataclysmic caldera collapse of
the so-called Archiflegrean volcano—that is,
bits of the ancient volcano rim as Big Archie
exploded 40,000 years ago, tore the roof off
itself and settled back to sea-level and
below. As you go through the area, you go
through Agnano, the Astroni, and other places,
all parts of the Campi
Flegrei, or Flegrean Fields. Flegrean
means "fiery." They are remnant volcanoes from
the so-called Second Flegrean Period (c.
20,000 ago), which featured the simply-named
Flegrean Volcano (bounded by the black lines
with wedges, centered on the town of
Pozzuoli). One area, the Solfatara,
is still wheezing if not active, but it could
erupt, they say. The Flegrean
Volcano produced the Posillipo
hill, the slopes of which attracted the Greeks,
then Romans and now a bunch of other optimists who
have never studied geology.  A
bit to the east, I (and thousands of
others—photo, right) live on the northern slope
of another earth-engine called the Chiaia
volcano (again, right where that word, "Chiaia"
is in the above image). It had not occurred to
me before, but as I look from my balcony to the
south, the postcard below me is a vast
amphitheater, a semi-circle with the Egg Castle
on the left and Mergellina on the right with
that western end of the amphitheater extending
out to a point called Cape Posillipo. The stage
below me (photo, below) is at sea-level and
Capri is dead ahead, a backdrop, 25 miles away.
From the slopes of the
ancient Chiaia crater, we
all have great seats for whatever is to come.
That original explosion was a piker compared to
Big Archie of some eons earlier, but it did form
what is now the Chiaia section of Naples and
most of the Vomero hill above it. From the sea, the Vomero
hill above me seems to run over to the west and
form a single long ridge with the Posillipo
hill. That is deceptive. They do run together,
after a fashion, but only because the Chiaia
volcano came first, and then the
smaller-than-Archie Flegrean volcano to the west
blew and spat out the Posillipo hill partially
on top of it.All of this volcanic activity has made the area rich in yellow tuff, a sandstone, the ubiquitous building material in Naples. I am currently in the midst of translating a book about the subsoil of Naples. Co-translator, Larry Ray, writes this in his presentation of the translation for the Napoli Underground website: "...the tuff sandstone strata are honeycombed with hundreds and hundreds of gigantic manmade cavities where the durable sandstone had been quarried and brought to the surface to build palaces, villas and other buildings over the centuries. Additionally other voids included railroad tunnels, ancient Greek and Roman aqueducts and water reservoirs, long tunnels from the city's pneumatic mail and message network from the early 1900's, as well as elaborate network of ancient as well as operating sewer lines, gas lines and other similar cavities." All of that is a cause for concern in construction around here. There is not an area in the city that is not undermined in some fashion or other. And maybe not even a building. We get earth slides and cave-ins frequently. I have learned to be as fatalistic about that as I am about volcanoes. My Chiaia explosion must have come from right where that rich guy’s yacht is anchored. If Chiaia goes “ka-blooey” (to use the technical geological term) again, he’s a goner. But, then, so am I. main index Science portal |